There's nothing with your game or account that is preventing you from appearing on our search. When you are trying to rank for "topic" based searches, there is a lot more competition, and the search UI isn't the greatest for that. We try to push people into the browse page with a tag for topic based browsing. Search at the moment works best for direct title matches. I just added an official "Soccer" tag to make it easier to find from search.
Regarding searching by your name, search works by your username, not your display name: https://itch.io/search?q=oliver+benedens
Hope that explains what's going on.